In wireless communications, different frequency bands are set aside by the Federal Communications Commission (FCC) for different purposes. Users of a particular frequency band may be primary or secondary, licensed or unlicensed. Existing users of a particular frequency spectrum are called incumbents of that spectrum. Secondary devices, such as unlicensed Cognitive Radio (CR) units, rely on dynamic spectrum access techniques to gain access to spectrum that is used by incumbents (e.g., primary licensed users), also called protected devices. For example, in the Television White Space (TVWS) spectrum, typical incumbents include television and wireless microphone transmitters.
The transmission characteristics of many licensed incumbent systems and devices are contained within regulatory databases such as the FCC's Consolidated Data Base System (CDBS) and the FCC's Universal Licensing System (ULS). Other incumbent users, such as authorized wireless microphone users or cable headend receivers may need to register with a particular database to obtain protection for their operations. These characteristics include transmitter location, effective radiated power (ERP), antenna patterns, and antenna height above average terrain (HAAT) in a variety of frequency bands. The FCC has issued operating rules for a number of different frequency bands. For example, the TVWS rules require that secondary devices operate in the television band access a geo-location database in order to determine open spectrum (i.e., channel availability) before selecting and transmitting on a particular channel. One example of a geo-location database is a TVWS databases. The geo-location databases, which typically cover overlapping geographic areas, may be run by different third-party vendors and offer different services in addition to determining the channel availability. According to regulatory guidelines, each vendor will be responsible for accessing the regulatory databases and computing incumbent protected service areas (i.e., contours) to determine channel availability at a particular location of the secondary device, based on the operating rules for the band.
However, there are a large number of steps and computations required to determine channel availability information. Moreover, the computation process is relatively loosely specified under current operating regulations. This may result in inconsistent incumbent protection results between the different geo-location databases due to various issues such as differing protection algorithm quantization/interpolation methods, geo-spatial reference points when channel availability results are gathered from multiple databases, or times in which the protection data in each geo-location database is updated. Moreover, the geo-location data or algorithms may become inadvertently or deliberately corrupted during operation. In any event, incorrect channel availability information may cause impermissible interference to protected devices if the secondary devices begin to operate in the desired location.
It is thus desirable to provide accurate and consistent results independent of the geo-location database queried.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments shown so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Other elements, such as those known to one of skill in the art, may thus be present.